The proposed research is designed to provide a detailed description of the effects of delta-9-tetrahydrocannabinol (delta-9-THC), the major psychoactive principle in marihuana, upon reproductive endocrine function in the female mammal. Ovariectomized and intact cyclic female rats will be acutely or chronically exposed to low doses of delta-9-THC and the effects of treatment on pulsatile luteinizing hormone (LH) secretion and the serum concentrations of LH, follicle stimulating hormone (FSH), and prolactin determined by specific radioimmunoassays. Indwelling atrial cannulae will be used to facilitate the withdrawl of small blood samples from indiviual alert and unrestrained animals in order to obtain hormonal information for an extended period following drug treatment rather than for only a single point in time. The techniques of brain stimulation an hypothalamic deafferentation, and the injection of exogenous luteinizing hormone releasing hormone (LHRH) will be employed to assess actions of delta-9-THC directly at the levels of the hyothalamus and pituitary, respectively. In addition, the effects of delta-9-THC on the ovulatory surge of LH and the luteotropic surges of prolactin will be examined and the functional significance of observed endocrine changes on the reporductive cycle, ovulation, and the maintenance of pregnancy or pseudopregnancy determined.